1. Field of the Invention
The present invention relates to a sunshade device for the ear door window of an automobile, in which a sunshade screen wound on a winding roll is electromotively spread so as to intercept sunlight transmitted through the rear door window of an automobile.
2. Description of the Prior Art
In general, the rear door window of an automobile has a transverse dimension smaller than a longitudinal dimension, unlike a rear windshield. That is to say, the rear door window of an automobile has a width less than its height. Due to this fact, it is difficult to apply such sunshade devices as disclosed in Korean Utility Model Registration No. 182090 and Korean Patent No. 425005 (corresponding to U.S. Pat. No. 6,668,902) to the rear door window of an automobile, each of said sunshade devices having a pair of actuation bars which can be erected or tilted while facing each other to raise or lower a sunshade screen rod, to which one end of the sunshade screen wound on the winding roll disposed in the frame mounted in the widthwise direction of the rear door window of an automobile is fastened.
To date, the sunshade device as disclosed in German Patent aid-open Publication No. DE3415930A1 has been applied to the ear door window of an automobile.
This sunshade device is constructed in a manner such that sunshade screen rod is raised and lowered by two telescopic bars capable of being extended or retracted, as in a well-known antenna assembly, to spread or wind a sunshade screen.
However, since the telescopic bars are relatively slender, when the telescopic bars connected to the sunshade screen rod are extended or retracted, they shake. Specifically, when the rear door window is lowered while an automobile is being driven, the shaking of the telescopic bars becomes more serious, and the sunshade screen flaps.
In the sunshade device, each of the flexible driving cables for extending and retracting the telescopic bars has spur gear teeth, and a driving gear, which comprises a spur gear meshed with the spur gear teeth of the driving cables, is provided to an output shaft to which a worm wheel meshed with a worm secured to the rotation shaft of an electric motor is secured.
As a consequence, because the conventional sunshade device employs a number of gears meshed with one another, a large amount of operation noise is generated, and the structure of the sunshade device is complicated.
Also, due to the fact that the flexible driving cable is movably inserted through a guide tube, the upward and downward movement of the sunshade screen rod is impeded to some extent.